package com.lp;

import java.util.HashMap;

public class MapTest {
    public static void main(String[] args) {
        HashMap<String,String> map = new HashMap<>();
        String put = map.put("a", "第一个值");
        map.put("b","第二个值");
        String put1 = map.put("a", "第一个值被改了");
        System.out.println(put);
        System.out.println(put1);
    }
}
